1. Technical Field
The present invention generally relates to processing digital imagery.
2. Background Art
Mosaics of digital images are created, among other reasons, to form substantially continuous views of landscape, terrain, sky, or other scenery. Individual digital images are processed and blended with each other to form the mosaic.
Ideally, the blended images appear seamless and the blending should not be apparent to the human eye. However, it is often the case that a mosaic contains blend artifacts, such as misaligned edges, different lighting, and/or different color compositions in adjacent blended images. Blend artifacts can, for example, cause a patchwork-like effect to be visible when the overall color tones of different images vary significantly.
The reduction of color differences among adjacent blended images can noticeably improve the viewing quality of the mosaic. However, conventional methods appear inadequate for color correcting large and/or dynamic mosaics. Conventional methods for correcting color differences, for example, rely on a reference image that is created with substantial manual effort from an original source image. The reference image is then used, with a technique such as color histogram matching, to color-correct images and/or areas of a mosaic to be corrected. Any updates to a source image can require the reference image to be updated again with substantial manual effort. Therefore, the relatively high levels of manual effort, for example, to generate reference images, and substantial dependence on source images and/or reference images, render conventional approaches unsuitable for applications involving large and/or dynamic mosaics.
In many instances, mosaics are large and are created from numerous source images. For example, Google Earth creates a mosaic representing the Earth having a large number of images. The source images used for the mosaic can change frequently as new images are acquired. Therefore, new methods and systems are needed for updating large and/or dynamic mosaics.